This invention relates to methods for detecting photons, radiations or neutrons using superconductors and methods for obtaining two-dimensional images thereof. The invention is particularly characterized by using MgB2 as a superconductor having isotopes that become adequately superconducting at the temperature of liquid helium. The invention also realizes imaging with high position resolution by using a two-dimensional imaging method that detects phonons with a superconductor sensor as they are generated from a superconducting or single-crystal detection medium. The invention is therefore applicable to the fabrication of sensors for use in experiments or analyses with photons shorter than a few microns, X-rays or neutrons. It also finds utility in analytical techniques that take advantage of its ability to detect both the incident energy and position of photons, radiations or neutrons.
An X-ray detector of high energy resolution using a Nb/Al/Al2O3/Al/Nb tunnel junction device has been developed by Matsumura et al. (Matsumura et al., Nucl. Instrum. & Methods, A329 (1993) 227) and other researchers and used as a superconductor-based radiation detector. An imaging detector for detecting the incident energy and position of a radiation with the intermediary of phonons generated from a superconducting or single-crystal radiation detection medium has been developed by Kurakado et al. (Kurakado et al., Rev. Sci. Instrum. 62 (1991) 156) and other researchers.
In the contemplated prior art technology, Nb has been used as a superconductor; particularly, in the case of detectors using a superconducting tunnel junction, it was necessary to cool them to a temperature about a tenth of the critical temperature before use but cooling to about 0.4 K was time-consuming and required an expensive apparatus. It has therefore been desired to develop a superconducting detector that can be operated at higher temperatures. In addition, neutron imaging detectors were scanty that used superconductors. What is more, it has been very difficult to develop an imaging detector capable of detecting X-rays or neutrons at high position resolution.